1. Technical Field
The present disclosure relates generally to a portable electronic device, and particularly to a built-in antenna of a portable device.
2. Description of the Related Art
A portable terminal (portable device) is generally considered any hand held electronic device capable of receiving and/or transmitting an information or communication signal. Today's ubiquitous portable devices such as smartphones typically perform a variety of function such as voice communication, short message transmission, a multimedia function such as playing music or reproducing video, and an entertainment function such as a game. Such portable terminals may be classified into various types considering specialized functions and portability thereof. For example, portable terminals are classified into a bar-type, a folder-type, a slider type, etc. based on external appearances thereof.
As the multimedia function has expanded, a recent trend is to configure portable terminals with a large display. In addition, as the degree of integration in electronic devices has increased and high capacity and ultra high speed wireless communication is popularized, a myriad of functions are integrated in a typical portable terminal. However, with the larger displays, when considering the portability, miniaturization and lightening of portable terminals are also desirable. Accordingly, in order to maintain ease of portability while increasing the display size, it is required to reduce the thickness of the portable terminal.
Meanwhile, portable terminals have in recent years been designed with a built-in antenna for wireless communication, rather than the protruding antennas of earlier models. In order to achieve a requisite radiation characteristic and suppress interference with other circuit devices, the antenna should be suppressed from interfering with a circuit board, a conductive component or an integrated circuit chip within the portable terminal.
FIG. 1 illustrates an installation structure, 10, of a conventional embedded antenna device of a portable terminal. An antenna device, more specifically, a radiator embedded in the portable terminal, is usually positioned to face a circuit board 11 at least partially. The installation structure 10 of the antenna device is the rear surface of the circuit board 11. In order to minimize the effect of an RF signal transmitted/received through a radiator to other circuit devices, it is desirable to maintain a predetermined gap between the radiator and the other circuit devices. In particular, when a ground surface 13 is provided over a major surface of the circuit board 11, a fill-cut region 15 (i.e., a region that is cut out and then filled) is formed by removing a part of the ground surface 13 on the circuit board 11 as illustrated in FIG. 1 so as to install an embedded antenna device. Typically, a portion of the radiator of the antenna device is disposed over the fill-cut region 15.
In addition, a connecting member 17 of an earphone socket, a universal serial bus (USB) connector, or the like is provided at an edge of the circuit board 11. Such a connecting member 17 is also fabricated to include a metallic material, and especially, a USB connector or the like, which includes connecting terminals arranged densely in the inside thereof, and is protected by a metallic case. FIG. 2 illustrates a connecting member 17, in particular a metallic case portion of the connecting member. When the case of the connecting member 17 is formed of a conductive material, it is desirable to ground the case itself to the ground surface 13 of the circuit board 11.
Even if such a case formed of a conductive material is connected to the ground surface 13, it is desirable to secure a sufficient gap between the circuit board and the antenna radiator. This is because the radiation characteristic of a given radiator varies considerably depending on the installation position, the proximity to other conductive components, and whether nearby conductive components are grounded or not.
Recently, as integrated circuits have been made smaller, the size of a circuit board 11 of a portable terminal has gradually decreased. The smaller size makes it more difficult to achieve a requisite connecting member mounting space, a fill-cut region 15 for disposing an antenna device, and so on. Accordingly, as illustrated in FIG. 1, the connecting member 17, more specifically, the case of the connecting member 17, is sometimes inevitably disposed on the fill-cut region 15 of the circuit board 11.
However, such an arrangement of the connecting member may limit a space or region 19 where an antenna device may be installed. That is, the flexibility in designing an antenna device is seriously degraded. Further, it is necessary to keep portable terminal thickness to a minimum in order to miniaturize and lighten the portable terminals as the sizes of displays increase, and the ability to provide a built-in antenna device capable of achieving a stable radiation performance has reached a limit. In addition, when a plurality of antenna devices are installed in a single terminal in order to use various types of communication standards, for example, mobile communication, WLAN (Wireless Local Area Network), Bluetooth™, and NFC (Near Field Communication), arranging all the antenna devices inside the portable terminal is even more challenging.